Kesterite materials, such as those containing copper (Cu), zinc (Zn), tin (Sn) and at least one of sulfur (S) and selenium (Se) (abbreviated herein as “CZT(S,Se)”), are inexpensive and earth-abundant. CZT(S,Se) is of current interest for use as a solar cell absorber material.
The most common form of CZT(S,Se) in high efficiency solar devices is polycrystalline. While the role of grain boundaries is not well understood, it is thought that grain boundaries in polycrystalline CZT(S,Se) absorber materials can undesirably lead to voltage problems in solar devices.
Thus, solar devices employing grain boundary-free forms of CZTS would be desirable.